Polarization resistance and galvanic current measurements, used for underground corrosion studies, are described, and problems encountered in making these measurements in the field, along with solutions, are discussed. Polarization measurements, supported by physical measurements, have shown that induced alternating current increases the corrosion rate of copper concentric neutrals compared to copper neutrals without ac. These measurements also revealed that driven piles undergo less corrosion attack than similar piles in backfilled trenches. Galvanic current measurements provide valuable information on the behavior of galvanically coupled materials and can be used to compare the corrosivity of soil environments.